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Abstract:

The present invention comprises a workpiece container for storing at
least one workpiece having a bottom surface and a peripheral edge. In one
embodiment, a workpiece support structure is located within the container
enclosure, which forms multiple vertically stacked storage shelves within
the enclosure. Each storage shelf includes, in one embodiment, a first
tine and a second tine for supporting the workpiece in a substantially
horizontal orientation. The bottom surface and peripheral edge of a
workpiece seated on a storage shelf extends beyond the outer edge of both
the first tine and the second tine. An end effector according to the
present invention may engage these extended portions or "grip zones" of
the workpiece.

Claims:

1. A substrate container for storing at least one substrate, comprising:
a housing assembly encompassing the at least one substrate, the housing
assembly having a container door for access into an inner region of the
housing assembly; a support structure disposed within the housing
assembly, the support structure having a plurality of support extensions
extending into the inner region of the housing assembly, the plurality of
cantilevered support extensions arranged as horizontally coplanar pairs,
wherein support extensions of different horizontal planes are vertically
aligned, and wherein access for transporting the substrate is provided
outside of each of the cantilevered support extensions, wherein the
plurality of cantilevered support extensions include support pads for
supporting a substrate.

2. The substrate container as recited in claim 1, wherein the support
structure is (a) molded as part of the container door, (b) molded as part
of the housing assembly, or (c) affixed to the housing assembly or
container door.

3. The substrate container as recited in claim 1, wherein the support
structure further comprises: a first base member extending upward from a
base of the housing assembly; and a second base member extending upward
from a base of the housing assembly.

4. The substrate container as recited in claim 3, wherein the first base
member and the second base member support corresponding ones of the
coplanar pairs.

5. The substrate container as recited in claim 1, wherein the support
structure further comprises: a first base member attached to the housing
assembly; and a second base member attached to the housing assembly.

6. The substrate container as recited in claim 1, wherein the support
structure further comprises: a first base member is affixed to the
container door; and a second base member is affixed to the container
door.

7. A substrate container for storing at least one substrate, comprising:
a housing enclosure; a support structure having a plurality of vertically
aligned support extensions, wherein spaced apart pairs of the plurality
of the vertically aligned support extensions support a substrate in a
substantially horizontal orientation, the spaced apart pairs being spaced
apart at a distance less than a diameter than the substrate and enabling
access to a first and a second area of the substrate for substrate
transportation, both the first and second area defined outside of the
spaced apart pairs; wherein the area is further defined on both sides of
a centerline of a backside of the substrate.

8. The substrate container as recited in claim 7, wherein the plurality
of vertically aligned support extensions are in a cantilever
configuration, or attach to the support structure behind the centerline.

9. The substrate container as recited in claim 7, wherein one of a distal
end or a proximal end of the support extensions includes a lateral
support limiting lateral movement of the substrate in the substrate
container.

10. The substrate container as recited in claim 7, wherein the housing
includes a base.

11. The substrate container as recited in claim 10, wherein the base
includes a first member extending upward from the base and a spaced apart
second member extending upward from the base, the first and the second
members located behind a centerline of the base, and wherein each of the
plurality of support extensions is affixed to one of the first or the
second members.

12. A substrate container for storing at least one substrate, comprising:
an enclosure having a top, a bottom, and a side connecting the top and
the bottom; a substrate support structure defined within the enclosure,
the substrate support structure having an array of support members
extending from a peripheral region of the container towards an interior
region of the container, wherein the substrate container is configured so
that a transport mechanism moving substrates to and from the substrate
container supports the substrate outside of the support members and
inside the side of the enclosure, wherein each of the support members
includes a proximal end attached to a rear interior surface of the
enclosure, or wherein each of the support members include a proximal end
affixed to vertical supports extending from the bottom.

13. A substrate container for storing at least one substrate having a
diameter and a peripheral edge, comprising: an enclosure defined by a
container shell and a mechanically openable bottom door; and a substrate
support structure forming a plurality of vertically stacked storage
supports within the enclosure, each vertically stacked storage support
for supporting a substrate in a substantially horizontal orientation, the
structure comprising: a first base member extending from the mechanically
openable bottom door; a second base member extending from the
mechanically openable bottom door; a first tine extending from the first
base member to a free-standing distal end; and a second tine extending
from the second base member to a free-standing distal end, the second
tine spaced apart from the first tine by a distance less than the
diameter of the substrate, wherein access for transporting the substrate
is provided outside of each of the tines; wherein the first tine and the
second tine include lateral supports on one of corresponding distal or
proximal ends to prevent lateral movement of the substrate.

14. The substrate container as recited in claim 13, wherein the access
for transporting the substrate is located on both sides of a centerline
of the substrate.

Description:

CLAIM OF PRIORITY

[0001] This application is a continuation application under 35 USC
§120 of U.S. patent application Ser. No. 11/483,366, filed on Jul.
7, 2006 entitled "Workpiece Support Structures and Apparatus for
Accessing Same", which claimed priority under 35 U.S.C. §119(e) to
U.S. Provisional Patent Application No. 60/697,528, entitled "End
Effector Tine and Transfer Methods," which was filed on Jul. 8, 2005,
both applications are incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention generally comprises workpiece support
structures and a workpiece transfer apparatus for accessing the
workpieces stored in the structures. More specifically, the present
invention comprises a structure for supporting the workpieces such that
the transfer device may randomly access any of the workpieces stored in
the carrier.

BACKGROUND OF THE INVENTION:

[0003] Conventional wafer containers, such as a Front Opening Unified Pod
(FOUP) or a Standard Mechanical Interface (SMIF) pod, often contain
shelves of fixed-pitch spacing to support the semiconductor wafers. FIG.
1 illustrates one embodiment of a conventional FOUP 10. The FOUP 10
includes a housing or shell 12 and a FOUP door 14 that mechanically
couples with the FOUP shell 12. The housing 12, which includes a top 18,
a back 20, a first side 22, a second side 24 and a bottom 26, defines an
enclosure 28. The enclosure includes a support 30 located on the interior
surface 32 of the first side 22 and the interior surface (not shown) of
the second side 24. Each support 30 includes multiple shelves 16. Each
slot between a pair of shelves 16 stores a single wafer. Each support 30
covers a portion of the wafer's peripheral edge while the wafer is seated
in the FOUP 10. Access to the outside edge of the wafer is blocked by the
shelf structure. Wafers are therefore typically handled by thin-bladed
end effectors that must reach between adjacent wafers and subsequently
either secure the wafer with a vacuum chuck or some type of edge support
and/or gripping arrangement. These methods of securing the wafer often
support the wafer by the wafer's back and front edges or elsewhere on the
back edges.

[0004] This conventional wafer securing approach has been in widespread
use in the semiconductor manufacturing industry for over twenty-five
years. But this approach has a number of shortcomings that become more
serious as the wafer size becomes larger. Also, increasing use is being
made of thinned wafers, which are prone to significant bending
deflections when supported by the edge.

[0005] Some of the deficiencies of conventional wafer support and carrier
architectures include:

[0006] 1) Wafer Mapping--Break-the-beam mapping has proven to be the most
reliable method of determining a wafer's presence or absence and its
vertical position within the container. However, break-the-beam mapping
with the 300 mm FOUP architecture requires expensive and complex
mechanisms to position sensing elements into the container.

[0007] 2) End effector blade travel zone--To access a wafer, the end
effector blade must first travel between adjacent wafers until it reaches
a desired position, and at that position, lift the wafer from the support
shelf. As wafer diameter increases, the mass of the wafer and the blade
length required to support the wafer also increases. To maintain
reasonable deflection characteristics of the end effector for larger
diameter wafers, the end effector blade must be thicker. If the thickness
of the end effector blade increases, the pitch between the wafers must
also increase to allow the thicker end effector to pass between wafers
without contacting the wafers. Either container size will have to
increase or fewer wafers can be stored in conventional containers.
Additionally, the extra travel length of the end effector is subject to
wafer bow, distortion and warping, as well as the vibration
characteristics of the end effector due to the rapid horizontal and
vertical motions required for time efficient wafer handling. All of this
must be accomplished without any accidental contact between a moving end
effector and a wafer. Contact between the end effector and a wafer will
likely to cause serious damage to sensitive circuits on the wafer as well
as generating particle bursts that may contaminate all the other wafers
in the container.

[0008] 3) End effector travel path efficiency--A conventional end effector
places a wafer in a container and then withdraws to enable vertical
motion clearance for randomly accessing the next wafer, which is then
withdrawn and taken to a process or metrology location. Thus, four
horizontal moves are required for each wafer exchange at the container.

[0009] 4) Process/Metrology chuck complexity--Typically, wafers are placed
on flat chucks or platens for processing or measurement. In many
applications, the wafer is secured to the chuck (and planarized) by
applying vacuum. Use of conventional vacuum or edge grip end effectors
necessitates large cutaway areas in the chuck to enable release of the
wafer and withdrawal of the end effector blade.

[0010] 5) Multiple wafer handling--It is very difficult in today's
architecture to pick or place multiple wafers simultaneously or to enable
individual selection of desired wafers in a mass transfer mode.

[0011] Thus, it would be advantageous to have an end effector with these
features. The various embodiments of an end effector and a tine structure
described herein provides such features.

SUMMARY OF THE INVENTION

[0012] One aspect of the present invention is to provide a new apparatus
for supporting semiconductor wafers or substrates. In one embodiment, the
present invention comprises a structure that enables storage and
transport of one or more wafers as well as random access pick and place
handling of individual wafers or groups of wafers.

[0013] Another aspect of the present invention is to provide a tine
structure that supports each wafer by a pair of cantilevered structures.
In one embodiment, the pair of cantilevered structures each include two
contact surfaces for supporting the wafer; one contact surface at the
distal end and the other contact surface at the proximal end. While a
wafer is seated on the cantilever structures, the peripheral edge of the
wafer is exposed or accessible by an end effector. A portion of the
wafer's bottom surface is also exposed or accessible by an end effector,
and in one embodiment is referred to as a "grip zone." In another
embodiment, each cantilever structure includes a third contact surface.

[0014] Yet another aspect of the present invention is to provide a tine
structure whereby an end effector may travel along the outside of the
support structure between wafers. In one embodiment, the pair of
cantilevered structures are spaced apart such that a portion of a wafer,
seated on the cantilever structures, extends out beyond the outer edge of
each cantilever structure. An end effector according to the present
invention may then travel between wafers along the outside of each wafer;
eliminating the need to travel across the entire wafer surface simply to
lift a wafer off the support shelves. In one embodiment, the end effector
travels along the outside of the wafer until the end effector is at a
height whereby the end effector arms can be positioned underneath the
wafer. This distance, by way of example only, comprises a few
millimeters, and does not require the end effector to travel across the
wafer surface.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1 provides a perspective view of a FOUP, according to the
prior art;

[0016] FIGS. 2A-2B provide a cross-sectional plan view and a side
elevation view of an embodiment of the present invention;

[0017] FIG. 3 provides a plan view of another embodiment of the present
invention;

[0018]FIG. 4 provides a perspective view of another embodiment of the
present invention;

[0019] FIG. 5 provides a perspective view of yet another embodiment of the
present invention;

[0020] FIG. 6 provides a perspective view of still another embodiment of
the present invention;

[0021] FIG. 7 provides a perspective view of another embodiment of the
present invention;

[0022] FIG. 8 provides a perspective view of yet another embodiment of the
present invention;

[0023]FIG. 9 provides a plan view of yet another embodiment of the
present invention; and

[0024] FIG. 10 provides a cross-sectional plan view of the container shown
in FIG. 10 in conjunction with one embodiment of an end effector
according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0025] For the purposes of describing this invention only, the workpiece
support structure 102 will be described in reference to a carrier or
container. A container or carrier may include, but is not limited to, a
moveable, closed or open structure used to hold, store, transport or
protect semiconductor wafers, substrates, flat panel displays and the
like. Such a container includes, but is not limited to, a wafer cassette,
a Standard Mechanical Interface (SMIF) pod, and a Front Opening Unified
Pod (FOUP). For containers that include mechanically openable doors, the
present invention may be used in conjunction with front opening and/or
bottom opening containers. Of course, the workpiece support structure 102
is not limited to such containers and may be used in conjunction with any
type of workpiece storage needs.

[0026] FIGS. 2 and 4-8 illustrate one embodiment of a support structure
102. In this embodiment, each support structure 102 includes a base
member 104 and multiple tines 106. Each tine 106 forms a cantilevered
structure extending or projecting from the base member 104. A tine 106
may comprise any shape including, but not limited to, a flat surface, a
shape having a rectangular cross-sectional area, a shape having a
circular cross-sectional area, and so on. FIG. 2A illustrates that each
tine 106 is separated by a distance d1, which in a preferred embodiment,
comprises 10 mm. The distance d1 may comprise other distances as well.
There is no ideal distance d1. The distance d1 simply must be large
enough such that a wafer W may be vertically lifted off a storage shelf
(e.g., tines 106b1 and 106b2 in FIG. 4) to a height whereby the wafer W
may be removed from the storage shelf, and the wafer does not contact the
storage shelf located directly above (e.g., tines 106a1 and 106a2 in FIG.
4).

[0027] FIGS. 4-8 illustrate the support structure 102 in use with a bottom
opening container. The base member 104 shown in FIG. 4 extends upward
from the container door 12. The base member 104 may comprise a structure
separate from the container door 12 or may comprise a structure that is
part of the container door 12.

[0028] Any number of tines 106 may extend or project from a base member
104, and the number of tines 106 simply determines how many wafers may be
stored in a carrier if the support structure is located within a carrier
(each pair of tines 106, or storage shelf, supports a single wafer). For
example, the wafer supports 102 shown in FIG. 4 each include a base
member 104 and four tines 106. Thus, the support structure 102 shown in
FIG. 4 may store up to four wafers W. Each wafer W is supported by a pair
of tines 106, which may be referred to as a storage shelf. FIG. 4
illustrates that the uppermost pair of tines 106a1 and 106a2 are not
occupied by a wafer; tines 106b1 and 106b2 are supporting wafer W1; tines
106c1 and 106c2 are supporting wafer W2; and tines 106d1 and 106d2 are
supporting wafer W3. Each pair of tines 106 preferably support the wafer
W in a substantially horizontal orientation so that the wafers W are
substantially parallel to each other. FIG. 4 shows that the tines 106 are
molded into the base member 104. Each tine 106 may also comprise a
separate component affixed or secured to the base member 104.

[0029] FIG. 2A illustrates that a tine 106 includes a first end or
proximal end 112, a second end or distal end 114 and an outer edge 107.
If the support structure 102 is located within a FOUP, the outer edge 107
of each tine 106 faces the interior of the container shell 12 (e.g.,
surface 32 of a FOUP side wall 22--as shown in FIG. 1). The tines 106
preferably support a wafer W with a minimum amount of contact with the
wafer's bottom surface or peripheral edge P. In this embodiment, each
tine 106 contacts or supports the wafer W with only two surfaces--a first
support 108 and a second support 110. The first support 108 is located at
or near the first end 112 of the tine 106. The second support 110 is
located at or near the second end 114 of the tine 106. It is within the
scope of the present invention for other portions of the tine 106 to
contact the wafer W. In addition, the first and second supports 108 and
110 may be located elsewhere along the tine 106. It is also within the
scope of the present invention for a tine 106 to have only one support
while other supports are provided by the base member 104. In a preferred
embodiment, each storage shelf includes at least three supports shared
between the base member(s) 104 and the two tines 106.

[0030] FIG. 2A further illustrates that a tine 106 may also include an
additional support 116. In the FIG. 2A embodiment, a structure 118
extends from the tine 106 somewhere between the proximal end 112 and the
distal end 114 of the tine 106. The additional support 116 is preferably
located at the distal end 119 of the structure 118, but may, of course,
be located anywhere along the structure 118. The additional support 116
provides an additional support point, and may be desirable when, for
example, the support structure 102 is storing thin wafers.

[0031] Unlike the storage shelves in a conventional container, the tine
106 supports a wafer, yet enables access to the wafer's perimeter P
located between the two support pads 108 and 110. FIG. 2A shows that the
wafer's perimeter P, and an area 120 of the wafer W, extend out beyond
the tine 106 between the support pads 108 and 110. The area 120 of the
wafer W that extends beyond, or overhangs, the tine 106 is referred to as
a "grip zone." The grip zone 120 provides an access area for an end
effector or other mechanical apparatus to contact or grip the wafer W
while the wafer W is seated on the pair of tines 106. The grip zone 120
is created because the distance d1 between the pair of tines (e.g., tines
106a1 and 106a2) is less than the diameter D of the wafer W. Thus, each
tine 106 passes under the wafer W.

[0032] Accessing wafers stored in a FOUP or SMIF pod with a conventional
end effector requires many complicated, precise movements. First, the end
effector is inserted into the FOUP storage area to a predetermined
position that aligns the end effector with the wafer it is going to
remove from the FOUP. To get to this predetermined position, the end
effector travels between adjacent wafers (e.g., wafers W1 and W2 in FIG.
2B) towards the back of the FOUP. The entire time, the end effector is
within millimeters of the wafer surface. The end effector then rises up;
contacting the bottom surface of the wafer, and proceeds to raise up
until the wafer is lifted completely from the shelf. The end effector,
with a wafer seated upon it, is then removed from the container without
contacting either of two adjacent shelves or the adjacent wafer. The end
effector operates within this narrow area (e.g., between the two adjacent
shelves) the entire time, and must not damage the wafer (e.g., contacting
either shelf).

[0033] A conventional end effector must travel within this narrow area
between adjacent wafers twice when the end effector drops off a wafer in
the FOUP and then immediately travels to another wafer within the FOUP.
For example, to drop off a wafer within the FOUP, the end effector
travels into the FOUP and lowers the wafer onto a storage shelf. The end
effector then retracts out of the FOUP; traveling out of the FOUP between
two adjacent wafers. Once the end effector clears the wafers, the end
effector shifts in a vertical direction and is inserted between two
different adjacent wafers. The end effector then repeats the same
movements to remove the new wafer from the FOUP. The end effector may
accidentally strike or contact a wafer and damage the wafer while
traveling between the wafers.

[0034] If the support structures 102 are located in a container (e.g., a
FOUP), the present invention eliminates the need for an end effector to
travel across the entire face of the wafer simply to position its support
pads under the wafer. At the very least, the end effector has to travel
across only a very small portion of each wafer to position its support
pads. By creating the "grip zones" 120, an end effector may travel
vertically within the FOUP enclosure along the outside of the wafer's
perimeter or peripheral edge. When, for example, an end effector reaches
the appropriate height to engage a wafer, the end effector arms only have
to move a small distance towards the wafer until the end effector's
support pads are positioned to support the wafer and lift the wafer off
the storage shelf. The end effector does not have to travel across the
entire face of the wafer to lift the wafer off the support shelf.

[0035] FIGS. 2A and 4 illustrate one embodiment of an end effector 200. An
end effector may comprise any structure that acquires, supports and
transports a wafer or any other article (e.g., reticle, FPD, etc.), and
is conventionally driven by, or attached to, a robotic mechanism (e.g.,
robotic arm). An end effector may passively acquire a wafer (e.g., end
effector include tines) or actively acquire a wafer (e.g., end effector
includes a gripper mechanism that moves between a wafer loading position
and a wafer contact position). In this embodiment, the end effector 200
includes a first arm 202 and a second arm 204. The first arm 202 includes
a first support pad 210 and second support pad 212. The second arm 204
includes a first support pad 214 and second support pad 216. In a
preferred embodiment, three or more support pads support a wafer. For
example, the first arm 202 may have two supports pads and the second arm
204 may have one support pad, or vice versa. The first and second support
pads 210 and 212 on the first arm 202, and the first and second support
pads 214 and 216 on the second arm 204, are spaced apart from each other.
It is within the scope of the present invention for the end effector 200
to include two or more support pads shared between the two arms 202 and
204.

[0036] The first and second support pads 210 and 212 on the first arm 202,
and the first and second support pads 214 and 216 on the second arm 204,
may be passive supports or active supports. If the supports are passive,
the support pads 210-216 remain in the position shown in FIG. 4 at all
times. In this case, a wafer W remains on the support pads 210-216 by
gravitational forces. If the support pads 210-216 are active supports, at
least one support, and preferably each support, moves between a wafer
loading position and a wafer gripping position. The wafer loading
position allows the wafer to be seated on the end effector. After the
wafer is seated on the end effector, the support pads moves towards the
center of the wafer until the support pads contact the peripheral edge of
the wafer.

[0037] The configuration of the end effector 200 and the arms 202 and 204
shown in FIGS. 2A and 4 are only for illustration purposes. The end
effector 200 may have other configurations and the arms 202 and 204 may,
for example, include only one support pad each or incorporate a
break-the-beam sensor system 230. A break-the-beam sensor is known within
the semiconductor manufacturing art and is often used to accurately map
the true position of each wafer stored in the container to provide
error-free, scrape-free placement and retrieval of wafers at random
access positions. Such a sensor system is well known within the art and
therefore does not require further disclosure herein.

[0038] In effect, the conventional end effector blade is eliminated; the
end effector does not travel within the interstitial spaces between
wafers. The arms 202 and 204 of the end effector structure may have any
reasonable thickness as required for minimizing deflection and
controlling vibration. The support pads 210 and 212 on the first arm 202
and the support pads 214 and 216 on the second arm 204 may be passive
retention/support surfaces or activated retention surfaces with motion in
the direction 232. If the end effector arms 202 and 204 cannot move in
the direction 232, the end effector 200 first travels in the direction
234 beneath the wafer until the support pads 210, 212, 214 and 216 are
located substantially underneath the wafer's "grip zone" 120. The end
effector 200 then moves vertically (e.g., direction 236 in FIG. 2B) to
engage the bottom surface 20 of the wafer W and lift the wafer W a
controlled amount off the storage shelf. The end effector 200 can then
withdraw the wafer W from the container.

[0039] If the end effector 200 has arms 202 and 204 that move in the
direction 232, the end effector 200 can freely travel in the vertical
direction 236 unimpeded by the presence or absence of wafers stored in
the container. In this case, the distance between the arms 202 and 204,
while each are located in a retracted position, must be greater than the
diameter D of each wafer stored in the container. In operation, the end
effector 200 travels first in the direction 234 until the supports of
each arm 202 and 204 are substantially vertically aligned with the "grip
zone" 120 of a wafer stored in the container. The end effector 200
travels in the vertical direction 236 until the arms 202 and 204 are
located at a desired wafer level. The arms 202 and 204 extend towards the
wafer until the support pads 210, 212, 214 and 216 are located
substantially in the positions shown in FIG. 1A. The end effector 200
moves upward in the vertical direction 236, lifting the wafer W off the
tines 106 prior to removing the wafer W from the container in the
direction 234.

[0040] FIG. 3 illustrates the end effector 200 shown in FIG. 2A in
operation with a wafer chuck 50. The wafer chuck 50 illustrates that
other semiconductor devices may accommodate the end effector 200. In
particular, the wafer chuck 50 includes four relief channels 52, 54, 56
and 58. Each relief channel is aligned such that the end effector 200 may
lower the wafer W onto the chuck 50 and no contact the wafer chuck 50.
Once the wafer W is seated on the chuck 50, the end effector arms 202 and
204 move laterally away from the chuck 50 in the direction 232 and then
retracts from the chuck 50 in the direction 234.

[0041] FIGS. 4-8 illustrate various embodiments of an end effector. FIG. 4
illustrates one embodiment of an end effector 200 with passive fingers.
The end effector 200 includes a body 201 having a first arm 202 and a
second arm 204. The first and second arms 202 and 204 are shown in FIG. 4
as curved structures. The body 201 and arms 202 and 204 may have
different shapes. The support pads 210, 212, 214 and 216 are each shown
having a flat contact surface 218 for contacting the bottom surface of
the wafer and a backstop surface 220 that, in effect, prevents the wafer
from sliding off the contact surface 218. Each support pad may have
different shaped contact surfaces that minimize the amount of contact
between the contact surface 218 and the wafer. The end effector 200 is
shown having an optional third finger 220 to provide additional support.
The third finger 222 includes a wafer contact surface 224.

[0042] In operation, the end effector 200 is positioned such that, when
the end effector 200 moves towards the wafer in direction 234, the
fingers 202 and 204 move under the grip zone 120 of the wafer to be
removed from the container. The end effector 200 moves forward until the
contact surfaces 218 of the support pads 210, 212, 214 and 216 are
located in substantially the position shown in FIG. 2A. At this point,
the end effector 200 moves upward until the wafer is initially seated on
the contact surfaces 218, and continues to move upward until the wafer is
raised off the storage shelf (e.g., pair of tines 106). The end effector
200 then retracts in the direction 234 until the wafer is removed from
the container.

[0043] FIG. 5 illustrates another embodiment of an end effector 300. The
end effector 300 includes a first arm 302 and a second arm 304. The first
arm 302 has a first support pad 310 and a second support pad 312. The
second arm 304 has a first support pad 314 and a second support pad 316.
The end effector 300 may also include a third arm 314 having a support
pad 315, which provides additional support.

[0044] FIG. 5 illustrates that each arm is pinned to the end effector body
301. The first arm 302 pivots with respect to the end effector body 301
about a pivot pin 320. The second arm 304 pivots with respect to the end
effector body 301 about a pivot pin 322. Each arm may be affixed to the
body 310 by other mechanical devices that allow the arms to rotate with
respect the end effector body 301. In this embodiment, the first arm 302
is rotated about pivot pin 320 by an actuator 324, while the second arm
304 is rotated about the pivot pin 322 by an actuator 326. FIG. 4
illustrates that the first arm 302 moves between a retracted position A
and a workpiece support position B. The second arm 304 also moves between
a retracted and workpiece support position.

[0045] With the first and second arms 302 and 304 each in a retracted
position (e.g., position A), the end effector 300 may travel vertically
within the container enclosure between wafers because the arms 320 and
304 move between the outer edge 107 of each tine 106 and the interior of
the container wall. Thus, the end effector 300 moves vertically between
wafers in the direction 236 without having to move in the direction 234
at all--reducing the travel time between wafers. In operation, the end
effector 300 stops at a wafer "pick" location. The arms 302 and 304 move
to position B, which places the support pads 310, 312, 314 and 316
underneath the wafer. The end effector 300 rises until the wafer is
seated on the support pads, and continues to rise to lift the wafer off
the storage shelf. The end effector 300 then retracts and removes the
wafer out of the container enclosure 28.

[0046] FIG. 6 illustrates another embodiment of an end effector 400. The
end effector 400 includes a body 401 having a first arm 402 and a second
arm 404. The first and second arms 402 and 404 are shown in FIG. 6 as
curved structures. The arms 402 and 404 may have different shapes. The
support pads 410, 412, 414 and 416 are each shown as a cylindrical
actuator having a slot 415. The support pads 410-416 may have other
shapes. The end effector 400 is shown having an optional third finger 420
with a support pad 424 for additional support.

[0047] In operation, the end effector 400 moves along directions 434 and
436 until the support pads 410-416 are positioned adjacent a wafer W. At
this point, the support 410-416 move in the direction R1 towards the
wafer W until each support pad contacts the peripheral edge of the wafer
W and effectively grips the wafer. In this embodiment, the wafer's
peripheral edge P fits into the slot 415 of each support pad. The end
effector 400 then moves upward along direction 436 to raise the wafer W
off the storage shelf. The end effector 400 then retracts in the
direction 434 until the wafer is removed from the container enclosure.

[0048] FIG. 7 illustrates another embodiment of an end effector 500. The
end effector 500 includes a first arm 502 and a second arm 504. The first
arm 502 has a first support pad 510 and a second support pad 512. The
second arm 504 has a first support pad 514 and a second support pad 516.

[0049] FIG. 7 illustrates that each arm is pinned to the end effector body
501. The first arm 502 pivots with respect to the end effector body 501
about a pivot pin 520. The second arm 504 pivots with respect to the end
effector body 501 about a pivot pin 522. Each arm may be affixed to the
body 501 by other mechanical devices that allow the arms to rotate with
respect the end effector body 501. The first arm 502 moves between a
retracted position A and a workpiece support position B. The second arm
504 also moves between a retracted position A and workpiece support
position B (not shown).

[0050] FIG. 8 illustrates an end effector 600. In this embodiment, the end
effector 600 is capable of rotating a wafer seated on the end effector
600 about the wafer's center. The end effector 600 includes a first arm
602 and a second arm 604. The first arm 602 includes a first support pad
610 and a second support pad 612. The second arm 604 includes a first
support pad 614 and a second support pad 616. Each support pad, in this
embodiment, comprises a rotatable support mechanism for rotating a wafer
seated on the end effector 600.

[0051] In this embodiment, the first arm 602 is rotatably attached to the
end effector body 601 by a pin 620. The second arm 604 is rotatably
attached to the end effector body 601 by a pin 622. A first actuator 624
rotates the first arm 602 about the pin 620. A second actuator 626
rotates the second arm 604 about the second pin 622. Thus, the first and
second arms 602 and 604 rotate between position A and position B. The
arms 602 and 604 may be rotatably secured to the body 601 in other
manners.

[0052] It is often necessary to rotate the wafer W about its vertical
centerline axis to read, for example, identification codes or to align
the geometrical fiducials, including notches, in the wafer perimeter P.
The end effector 600 shown in FIG. 8 is only an exemplary embodiment of
an end effector with rotatable support pads 610, 612, 614 and 616 for
rotating the wafer W on the end effector 600. Likewise, the mechanism
used for reading identifying marks on the top or bottom surfaces of the
wafer perimeter can be enabled by utilizing an imaging device (camera) or
other reading means mounted on the end effector. Accomplishing this
"in-situ" saves time and floor space, and reduces cost and mechanism
complexity.

[0053] The various embodiments of the end effectors described herein allow
the arms of the end effector to move vertically external to the wafer's
peripheral edge P. Thus, almost all of the wafer support surface of a
process or metrology tool chuck may be used to support the wafer and does
not need, in large part, to accommodate the end effector blade (e.g.,
arms and body). FIG. 3 illustrates one embodiment of a metrology or
process tool chuck 50 in operation with the end effector 200. In this
embodiment, the chuck 50 includes a body 62 having a wafer support
surface 51, four indentations or channels to accommodate each support
pad, a first slot 60 and a second slot 63. FIG. 3 illustrates a wafer W
seated directly on the surface 51. It is also within the scope of the
invention to have lift pins, or other support structures, extending from
the surface 51 for supporting the wafer W above the surface 51. The wafer
W may be secured on the support surface 51 (or other support structure)
by any method known in the art including, but not limited to, vacuum,
gravity or electrostatic attraction.

[0054] To accommodate the arms 202 and 204 of the end effector 200, the
chuck body 62 includes a recessed area or channel to allow each arm to
pass through the chuck body 62 after the end effector 200 places the
wafer on the surface 51. For example, the chuck body 62 includes a
recessed surface 52 to allow the support pad 214 pass through the chuck
body 62, a recessed surface 54 to allow the support pad 216 pass through
the chuck body 62, a recessed surface 56 to allow the support pad 212
pass through the chuck body 62, and a recessed surface 58 to allow the
support pad 210 pass through the chuck body 62. In operation, the end
effector 200 places the wafer W on the surface 51 and keeps traveling
vertically downward into the chuck body 62. The end effector must retract
from the chuck 50 to allow the chuck to spin the wafer W. If the arms 202
and 204 cannot move away from the chuck body 62 in the direction 232, the
end effector would not be able to retract from the chuck 50 in the
direction 234. In one embodiment, each recessed surface travels
completely through the chuck body 62 such that the end effector may
effectively pass through the bottom surface of the chuck body 62 and then
retract in the direction 234 away from the chuck 50.

[0055] Alternately, the chuck body 62 includes a first horizontal slot 60
and a second horizontal slot 63 each located at a predetermined elevation
below the surface 51. The slots allows the end effector to lower the arms
202 and 204 to an elevation aligned with the slots 60 and 63, and
subsequently retract in the direction 234 away from the chuck 50 through
the slots 60 and 63. Arm 202 passes through the chuck body 62 within the
slot 60 and the arm 204 passes through the chuck body 62 within the slot
63. If the end effector 200 includes a third arm 222 (as shown in FIG.
3), the chuck body 62 includes a fifth recessed surface 65 to accommodate
the third arm 222. In operation after the end effector 200 places the
wafer W on the surface 51 the end effector continues to travel vertical
downward and the arm 222 will pass through the body 62 within the
recessed surface 65. Each recessed surface in the chuck body 62 takes
away a small amount of the support surface 51. However, the reduction in
the support surface 51 due to the recessed surfaces is minimal.

[0056] In semiconductor processing, wafers often have a starting thickness
of 0.7 mm-1.0 mm. The wafers are then thinned to a thickness of less than
0.3 mm at some intermediate stage of the total manufacturing process
sequence. The thinned wafer is very flexible and fragile, and the
historical methods of wafer edge support in a container as well as the
conventional edge gripping methods, are not adequate.

[0057] Each storage shelf supports a wafer at multiple points. In
particular, each storage shelf preferably supports a wafer by at least
three contact points or support pads. In one embodiment, a storage shelf,
which comprises two tines 106, includes a single support pad on each tine
106 (e.g., support pad 110) and a support pad located on each base member
104 (e.g., support pad 108)--all at substantially the same elevation in
order to support a wafer in a horizontal orientation. In another
embodiment, each tine 106 includes an additional support pad (e.g.,
support pad 116) to provide additional support. Of course, each tine 106
and/or base member 104 may include additional support pads. The number
and geometry of additional support pads for both the end effector and the
storage shelves is limited only by the requirement for the end effector
to interact with each tine 106.

[0058]FIG. 9 illustrates one embodiment of a wafer support structure 202
within a conventional FOUP 10. The FOUP 10 includes a housing or shell 12
and a FOUP door 14 that mechanically couples with the FOUP shell 12. The
housing 12, which includes a top 18, a back 20, a first side 22, a second
side 24 and a bottom 26, defines an enclosure 28.

[0059] In this embodiment, the support structures 202 are affixed to the
top 18 and bottom 26 of the FOUP shell 12. For example, the top end 203
of each support structure 202 is affixed to the top 18 of the FOUP shell
12 by three fixtures 205. The bottom end (not shown) of the support
structure 202 is fixed to the bottom 26 of the FOUP shell 12. It is also
within the scope of the present invention for the support structures 202
to be affixed to either the top 18 or the bottom 26 of the FOUP shell 12,
or be affixed to the FOUP shell 12 by other methods. Each support
structure 202 may also be molded with the FOUP shell 12. For example,
each base member 204 may be molded into the back 20 of the FOUP shell 12,
or any of the other surfaces of the FOUP shell 12 (e.g., top 18, bottom
26, first side 22, second side 24, etc.). In another embodiment, the
support structure 202 may not include a base member 204. Instead, each
storage shelf comprises one or more tines 206; each affixed or molded
into the FOUP shell 12. For example, the proximal end 214 of each tine
206 may include a pair of tabs that lock into a pair of slots located in
the back 20 of the FOUP shell 12. FIG. 9 illustrates that the two support
structures 202 comprise two separate structures. However, any portion of
the support structures 202, such as the base members 204 and/or tines
206, may comprise a single piece of material.

[0060]FIG. 9 illustrates one embodiment of a storage shelf, comprising a
pair of tines 206, for exemplary purposes. Each tine 206 extends or
projects from the base member 204. The tine 206 includes a first end or
proximal end 214 and a second end or distal end 216. The combination of
the two tines 206 and the base members 204 support a single wafer W with
six support pads--two support pads 208, two support pads 210 and two
support pads 212. The support pad 210 is located at or near the distal
end 216 of each tine 206. The other four support pads 208 and 212 may be
located on either the proximal end 214 of the tine 206 or the base
members 204, or a combination of the two. It is within the scope of the
present invention for other portions of the tine 206 to contact the wafer
W or for the support pads to be located in other positions.

[0061]FIG. 9 illustrates that the wafer's peripheral edge P, and a
portion of the wafer W, overhangs or extends beyond the outer edge 207 of
each tine 206 between the support pads 208 and 212--while the wafer W is
seated on the storage shelf. As discussed above, this overhanging portion
of the wafer W is referred to as the "grip" or "access" area that may be
engaged by an end effector while the wafer W is seated in the FOUP 10.

[0062] FIG. 10 illustrates an end effector 700 inserted into the FOUP 10.
The end effector 700 includes a body 701, a first arm 702 and a second
arm 704. The body 701 may be connected to, by way of example only, a
robotic arm for moving the end effector body 701 through any number of
movements (e.g., six degrees of freedom motion). The first arm 702 has a
proximal end 706 and a distal end 708. The second arm 704 includes a
proximal end 707 and a distal end 709.

[0063] The FIG. 10 embodiment of the end effector 700 includes two support
pads on each arm. The first arm 702 includes a support pad 710 located a
the proximal end 706 and a second support pad 712 located at the distal
end 708. The second arm 704 includes a support pad 714 located a the
proximal end 707 and a support pad 716 located at the distal end 709.
Each arm may include any number of support pads, and each support pad may
be located anywhere along the end effector's arms. It is preferable that
the support pads do not interfere with the support structure 202. FIG. 10
illustrates each support pad 710-716 as a passive pad. Alternately, each
support pad 710-716 may comprise an active pad similar to the end
effector embodiments shown in FIGS. 4-8.

[0064] When the end effector 700 is placed into the FOUP enclosure 28, the
arms 702 and 704 contour around the wafer's peripheral edge P--as shown
in FIG. 10. In a preferred embodiment, the distance between the wafer's
peripheral edge P and each side of the FOUP shell 12, such as the first
side 22 and the second side 24, is large enough so that the arms 702 and
704 of the end effector 700 may travel vertically within the enclosure 28
without contacting any part of the support structure 202 or the wafer W
or the FOUP shell 12. It is also within the scope of the present
invention for this distance to be minimal (as shown in FIG. 10) such that
arms 702 and 704 of the end effector 700 may not travel vertically within
the enclosure 28 without contacting any part of the support structure 202
or the wafer W. Thus, after setting a wafer on a storage shelf, the end
effector 700 would have to travel out of the enclosure, and raise/lower
to another elevation before the end effector 700 can be inserted back
into the enclosure 28.

[0065] Unlike a conventional end effector, the arms 702 and 704 preferably
do not travel under a wafer in order to place the contact pads 710-716
under a wafer or lift a wafer from a storage shelf. Maintaining the arms
702 and 704 on the outside of the wafer W eliminates the possibility that
either of the arms 702 or 704 will contact and/or damage the surface of a
wafer seated in the FOUP 10. The shape of the arms 702 and 704 shown in
FIG. 10 is for exemplary purposes only. The arms 702 and 704 may comprise
other shapes and/or configurations.

[0066] The arms 702 and 704 of the end effector 700 also preferably
contour around each tine 206. If the support pads 710-716 are active pads
(e.g., able to move towards/away from the wafer's peripheral edge P), the
end effector 700 may be placed into the FOUP enclosure 28 at any height
and subsequently move vertically to another elevation within the FOUP 10
without having to first withdraw from the FOUP enclosure 28. With the
support pads retracted, the end effector 700 may travel to its desired
position. Once the end effector 700 reaches a desired location, the
support pads 710-716 extend towards the wafer until a portion of each
support pad 710-716 is located below the wafer W. This way, the wafer W
will be supported (preferably in a horizontal orientation) when the end
effector 700 lifts the wafer W off the tines 206 or storage shelf and
removes the wafer W from the FOUP 10.

[0067] It should be appreciated that the above-described tine systems and
end effectors are for explanatory purposes only and that the invention is
not limited thereby. Having thus described a preferred embodiment of a
tine system and end effector, it should be apparent to those skilled in
the art that certain advantages of the within system have been achieved.
It should also be appreciated that various modifications, adaptations,
and alternative embodiments thereof may be made within the scope and
spirit of the present invention. For example, the storage shelves and end
effector have been illustrated in a semiconductor fabrication facility,
but it should be apparent that many of the inventive concepts described
above would be equally applicable to be used in connection with other
non-semiconductor manufacturing applications. It should be apparent that
the storage shelves are also not limited to workpiece carriers.

Patent applications by Anthony C. Bonora, Portola Valley, CA US

Patent applications in class Having plural grooves for retaining wafers

Patent applications in all subclasses Having plural grooves for retaining wafers